High-intensity vs. endurance workout--which is the victor?

Endurance training and high-intensity workouts--do both offer cardiovascular benefits? A study finds that each form of exercise has health benefits, with intense workouts perhaps edging out the competition.

The study focused on a group of 47 adolescents (average age about 16) who were assigned to a moderate exercise group, a high-intensity exercise group or a control group for seven weeks. The moderate exercise group did 20 minutes of steady running three times a week, while the high-intensity group did four to six repeats of an all-out sprint with brief recovery periods three times a week.

Both groups showed evidence of cardiovascular benefits at the end of the study. The high-intensity group had substantial improvements in systolic blood pressure, aerobic fitness and body mass index. Among the moderate-intensity group's improvements were aerobic fitness, body fat percentage, body mass index and insulin concentrations. No injuries were reported.

The moderate-intensity group burned more calories than the high-intensity group: 4,410 versus 907 on average. But the study authors noted that the high-intensity group exercised for a total of only 63 minutes, 15% of the 420 minutes spent by the moderate-intensity group.

Most exercise experts recommend that workouts include both endurance and interval training, which can be done outside or in a gym.

Although this was a small study, lead author Duncan Buchan of the University of the West of Scotland was optimistic about the implications of the results: "This is the first study to demonstrate the effects of a novel interval training program on both traditional and novel (cardiovascular disease) risk factors in adolescents," he said in a news release. "Larger scale and extended interventions must be undertaken so that the long term impact and effects of intermittent training programs on unfavorable metabolic profiles may be investigated further."